Strapping devices are used to wrap piles of boxes for example tightly so that the piles of boxes are maintained in a stable status which is benefit when transportation. In order to ensure the piles of boxes will not fall downwardly, the operators have to check the piles of boxes to prevent the higher portion of the piles of boxes from suddenly falling to injure the operators so that the conventional strapping devices are developed to have the function of loosening the strap slightly and still holding the boxes if the strapping devices are not operated to loosen the straps completely. Two known strapping device having such function are disclosed applicant's U.S. Pat. No. 5,778,496 issued on Jul. 14, 1998 and U.S. patent application Ser. No. 08/901,758, filed on Jul. 28, 1997 which is under the procedure of issuance. Both the two strapping devices resolve the problems described above, However, they include so many parts which increase weight of the strapping device so that are inconvenient for the operators to handle. Furthermore, the more the parts are included, the higher maintenance expense is needed.
The present invention provides a strapping device including fewer parts and easily to be operated so that the shortcomings mentioned above are properly mitigated.